|
| |
|
|
A001836
|
|
Numbers n such that phi(2n-1) < phi(2n), where phi is Euler's totient function A000010.
(Formerly M5429 N2359)
|
|
1
|
|
|
|
53, 83, 158, 263, 293, 368, 578, 683, 743, 788, 878, 893, 908, 998, 1073, 1103, 1208, 1238, 1268, 1403, 1418, 1502, 1523, 1658, 1733, 1838, 1943, 1964, 2048, 2063, 2153, 2228, 2243, 2258, 2363, 2393, 2423, 2468, 2558, 2573, 2633, 2657, 2678
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
REFERENCES
|
V. L. Klee, Jr., Some remarks on Euler's totient function, Amer. Math. Monthly, 54 (1947), 332.
_Jeffrey Shallit_, personal communication.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
|
|
|
LINKS
|
T. D. Noe, Table of n, a(n) for n = 1..1000
Don Reble, Python program
|
|
|
MATHEMATICA
|
Select[Range[3000], EulerPhi[2#-1]<EulerPhi[2#]&] (* From Harvey P. Dale, Apr 01 2012 *)
|
|
|
PROG
|
(PARI) is(n)=eulerphi(2*n-1)<eulerphi(2*n) \\ Charles R Greathouse IV, Feb 21 2013
|
|
|
CROSSREFS
|
Cf. A000010.
Sequence in context: A125876 A136065 A212420 * A144939 A118149 A214230
Adjacent sequences: A001833 A001834 A001835 * A001837 A001838 A001839
|
|
|
KEYWORD
|
nonn,nice
|
|
|
AUTHOR
|
N. J. A. Sloane.
|
|
|
EXTENSIONS
|
Corrected and extended by Don Reble (djr(AT)nk.ca), Jan 04 2007
|
|
|
STATUS
|
approved
|
| |
|
|
